Fuel feed system for internal combustion engines



B. C. PHILLIPS Feb. 22, 1966 FUEL FEED SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed April 22, 1964 3 Sheets-Sheet 1 INVENTOR. BERNARD L". PHILLIPS.

Mu 0W ATTY.

B. C. PHILLIPS Feb. 22, 1966 FUEL FEED SYSTEM FOR INTERNAL COMBUSTION ENGINES 3 Sheets-Sheet 5 Filed April 22, 1964 'IHIII15/ Z INVENTORY BERNARD L". PHILLIP 5.

vm l bmwm United States Patent 3,236,217 FUEL FEED SYSTEM FOR INTERNAL COMBUSTION ENGINES Bernard C. Phillips, Toledo, Ohio, assignor to The Tillotson Manufacturing Company, Toledo, Ohio, a corporation of Ohio Filed Apr. 22, 1964, Ser. No. 361,838 3 Claims. (Cl. 123-136) This invention relates to a fuel feed system for an internal combustion engine and more particularly to a novel fuel feed system particularly usable with engines of the reciprocating piston type wherein the fuel feed system embodies a fuel pump operable by differential fluid pressure.

It has been conventional practice on fuel feed systems for chain saw engines to employ a pulse operated diaphragm pump for supplying fuel to a diaphragm type carburetor, the motivating medium for actuating the pump diaphragm being the differential pressures or pulsations existent in the crankcase of a two cycle engine. It has been found that a pulse operated pump wherein the pump chamber is connected with the engine crankcase of a two cycle engine functions satisfactorily to pump fuel in suflicient quantities to take care :of the engine requirements at all speeds. Such pulse operated pumps have not heretofore been successfully operable with four cycle engines as the crankcase of a four cycle engine is vented and differential pressures developed are of sufficient magnitude to satisfactorily vibrate or oscillate a fuel pump diaphragm under all operating conditions.

The present invention embraces a method and arrangement of fuel feed system particularly for use with four cycle type engines wherein the varying pressures in a cylinder or combustion region of a reciprocating piston engine are utilized to actuate the diaphragm of a diaphragm type fuel pump to supply fuel to a charge forming device or apparatus for the engine.

Another object of the invention resides in a fuel feed and charge forming apparatus embodying a fluid pulse operated fuel feed device adaptable for use with any type of four cycle engine, the arrangement eliminating mechanical actuating means for a fuel pump.

Another object of the invention resides in a pulse operated fuel feed system which is usable for supplying fuel to a carburetor of the diaphragm type embodying a pumping diaphragm controlling fuel flow into the carburetor or for supplying liquid fuel to a carburetor of a constant level type eliminating the use of a metering diaphragm.

Further objects and advantages are within the scope of this invention such as relate to the arrangement, operation and function of the related elements of the structures, to various details of construction and to combinations of parts, elements per se, and to economies of manufacture and numerous other features as will be apparent from a consideration of the specification and drawing of a form of the invention, which may be preferred, in which:

FIGURE 1 is an elevational view of an engine of the four cycle type partly in section illustrating a form of fuel feed and charge forming apparatus associated therewith adapted to perform the method of the invention;

FIGURE 2 is a top plan view of the charge forming apparatus and fuel pump mounted on the engine intake manifold;

FIGURE 3 is an end view of the carburetor and fuel pump construction and illustrating the pulse tube connection;

FIGURE 4 is a fragmentary detail sectional view taken substantially on the line 4-4 of FIGURE 2;

FIGURE 5 is a longitudinal sectional view taken substantially on the line 5-5 of FIGURE 2;

FIGURE 6 is a transverse sectional view taken substantially on the line 6-6 of FIGURE 5;

FIGURE 7 is a side view of a combined overflow type carburetor and fuel feed pump;

FIGURE 8 is an end view of the construction shown in FIGURE 7;

FIGURE 9 is a bottom plan view of the construction shown in FIGURE 7;

FIGURE 10 is a sectional view taken substantially on the line 10-10 of FIGURE 9 and illustrating a fuel tank and connections with the fuel pump;

FIGURE 11 is a longitudinal horizontal sectional View taken substantially on the line 11-11 of FIGURE 7;

FIGURE 12 is a transverse sectional view taken substantially on the line 12-12 of FIGURE 11, and

FIGURE 13 is a detail sectional view taken substantially on the line 13-13 of FIGURE 11.

The fuel feed and charge forming arrangement is particularly usable with an engine of the four cycle type as the pulse for actuating the pumping diaphragm are obtained from differential pressures within the engine combustion region or cylinder without the use of mechanical components or means for actuating the pumping dia phragm.

Referring to the drawings in detail and initially to FIGURE 1, the fuel feed system and charge forming apparatus are illustrated in connection with an engine of the four cycle type wherein the varying pressures or pressure pulses existing in the combustion chamber of the engine during the intake and exhaust strokes of the piston are utilized as motivating media for actuating a.

pumping diaphragm for feeding fuel from a tank to a charge forming device. The internal combustion engine illustrated in FIGURE 1 comprises a base 10 supporting a crankcase 12 to which is secured a cylinder 14 of the air cooled type having heat dissipating fins 15 of conventional character. The cylinder 14 is provided with a head 17 equipped with a spark plug 18 for igniting combustible mixture in a combustion chamber 20 formed in the cylinder head.

Journally supported in the crankcase 12 is a crank shaft 22 having a crank pin 23 to which is secured a connecting rod 24, the latter being connected with the wrist pin 25 of a piston 26. The engine is inclusive of a cam shaft 28 journally mounted in the crankcase and driven at one half crank shaft speed through the medium of spur gears 30 and 32. The cam shaft 28 is provided with a cam 34 operating a valve lifter 35 which actuates a poppet valve 38 to admit combustible mixture into the combustion chamber 20 through an inlet manifold 40.

An expansive coil spring 42 normally urges the inlet valve toward closed position. The cam shaft 28 is also provided with a second cam (not shown) for operating an exhaust valve (not shown) in a conventional manner for exhausting burned gases from the cylinder 14 after the power stroke of the piston. The operation of the engine shown in FIGURE 1 is that of a conventional four cycle type.

One form of charge forming apparatus or carburetor and fuel feed or fuel pumping means is illustrated in FIGURES 1 through 6. The charge forming apparatus or carburetor 48 is of the diaphragm type and includes a body or body member 50 formed with a mixing passage 52 provided with a Venturi having a restricted region or choke band 54, the mixing passage having an air inlet region 56 and a mixture outlet region 58.

The outlet end of the body 50 is fashioned with a mounting flange 60 adapted to mate with a flange 62 formed on the engine manifold 40 and secured thereto by bolts 64.

The air inlet end of the carburetor body may be equipped with an air filter (not shown) of conventional construction. Iournaled in openings in the wall of the body adjacent the air inlet region 56 is a shaft 66 supporting a disc-like choke valve 67, a portion of the shaft 66 exteriorly of the body 50 being provided with a manipulating arm 68 shown in FIGURE 2, for operating the choke valve. Extending across the mixture outlet region 58 is a shaft 70 journaled in hores formed in the wall of the body 50, the shaft supporting a disc-like throttle va ve 72 for controlling flow of fuel and air mixture to the engine.

The throttle shaft 70 is provided with a manipulating arm 74. A second arm 75 fixed on the opposite end of the shaft 70 is adapted to engage an adjustable screw 76 carried by the body for determining the engine idling position of the throttle valve 72. The body '50 is formed with a recess providing a shallow fuel chamber 80 of circular configuration. A flexible membrane or diaphragm 82 extends across the recess and forms a flexible wall of the chamber 80, as particularly shown in FIGURES 5 and 6. An annular gasket 83 is disposed between the diaphragm 82 and the body 50.

A member 86 is disposed beneath the diaphragm 82 and is fashioned with a central recess 87 to accommodate flexing movements of the diaphragm 82. The member 86 forms a component of a fuel feeding or pumping means hereinafter described. The chamber 87 beneath the diaphragm 82 is vented to the atmosphere through an air passage 88, shown in FIGURE 5, to establish atmospheric pressure at the dry side of the diaphragm. The diaphragm 82 is made of highly flexible, thin material such as an impervious resin film or fashioned of a fine mesh fabric coated with an impregnant such as synthetic rubber or resin to render the diaphragm impervious.

Disposed within a recess 90 forming a part of the fuel chamber 80 is a lever 92 fulcrumed intermediate its ends upon a pin 94 carried by the body 50. The long arm of the lever is adapted to be engaged by a headed member or rivet 96 mounted at the central region of the diaphragm 82. Reinforcing discs 97 and 98 are disposed at opposite sides of the diaphragm and the headed member 96 has a tenon portion extending through the diaphragm and the discs and is riveted as shown in FIGURE 6 to secure the member 96 to the diaphragm.

The short arm 100 of the lever 92 engages an end of a fuel inlet valve member 102 shown in FIGURE 6. The carburetor body is provided with a threaded bore receiving a threaded fitting or valve cage 104 in which is slicla'bly disposed the valve body 102, the latter being of polygonal cross section to facilitate fuel flow past the valve.

The valve body 102 has a cone-shaped or needle valve portion 106 extending into and cooperating with a port 107 provided by an annular valve seat 108. The port 107 is in communication with a fuel inlet channel 110 which receives fuel from a fuel pump to be hereinafter described.

A spring 112 engaging the lever normally biases the inlet valve 106 toward closed position. The carburetor body 50 is fashioned with a main orifice or outlet 116 opening into the restricted region 54 of the Venturi for delivering fuel into the mixing passage for normal and high speed engine operation, and secondary orifice means, the latter means including an idling orifice 118 for engine idling operation and a low speed orifice 120. The engine idling and low speed orifices 118 and 120 open into a supplemental chamber 122 which receives fuel through suitable channel means (not shown) in communication with the fuel chamber 80.

Associated with the fuel channel means is an adjustable needle valve 124 (shown in FIGURE 2) for regulating fuel flow to the secondary orifices 118 and 120 in a conventional manner. The fuel delivered through the main orifice 116 is conveyed through a system of channels in communication wit-h the fuel chamber 80, one of said channels being illustrated at 126 in FIGURE 5. Associated with the fuel channel system for the .main orifice 116 is a manually adjustable needle valve 130 for regulating fuel flow to the main orifice 116 in a conventional manner.

The needle valve arrangement for adjusting fuel deliveiy to the main orifice 116 cooperates with the fuel channel 126 in a manner whereby the fuel forms a capillary seal or liquid fuel block to prevent back bleeding of air through the main orifice 116 when the secondary orifices are delivering fuel into the mixing passage. An arrangement of this character providing a capillary seal is disclosed in my patent, No. 2,841,372. It is to be understood that other types of valve means may be employed in association with the main orifice or nozzle to prevent back bleeding of air through the main orifice when the secondary orifices are delivering fuel to the mixing passage.

The operation of the carburetor shown in FIGURES l, 2, 5 and 6 is as follows: Aspiration or reduced pressure in the mixing passage established by engine suction in the inlet manifold 40, shown in FIGURE 1, acts upon the diaphragm 82 in the unvented fuel chamber 80 to move the diaphragm upwardly, as viewed in FIGURES 5 and 6, the diaphragm moving the lever 92 in a counterclockwise direction about its fulcrum to permit the inlet valve 102 to move away from the port 107 and admit fuel into the fuel chamber 80.

At normal or high engine speeds with the throttle valve 72 in a substantially opened position, fuel is delivered by aspiration from the fuel chamber 80 past the needle portion of valve member 130 through the main orifice 116 into the mixing passage and is mixed with the air moving through the passage. When the throttle valve is in engine idling position, fuel flows from the chamber 80 into the supplemental chamber 122 thence through one or both orifices 118 and 120 into the mixing passage, the liquid fuel at the needle portion of valve 130 providing a capillary seal to prevent back bleeding of air through the main orifice.

The carburetor 48 is associated with a fuel pump or fuel feeding means for maintaining fuel pressure in the fuel inlet channel 110 of the carburetor whereby fuel is available at all times during engine operation at the port 107 to be delivered into the carburetor when the inlet valve 102 is opened. Arranged adjacent the plate or member 86 is a member 134. The member 86 is formed With a cavity or recess providing a pumping or pulsing chamber 136, and the member 134 is formed with a cavity providing a fuel receiving compartment or chamber 138. A pumping diaphragm or membrane is disposed between members 86 and 134 and extends across the cavities 136 and 138 forming a flexible Wall between the chambers 136 and 138.

The pump body component 134 is provided with an annular portion 139 defining a recess arranged to receive a circular closure member 142 preferably formed of molded nylon or other material, the member 142 having a tubular projection 144 adapted to be connected with a fuel supply tank (not shown) by a flexible tube 146. Disposed at the periphery of the closure 142 is a gasket 148 engaging a fine mesh screen or filter 150, the central region of the filter engaging a shoulder on a boss 152 formed on member 134. The space 154 between the closure 142 and the filter forms a sump for foreign particles filtered out of the fuel.

A threaded bore in the boss 152 accommodates a securing screw 156 for retaining the closure 142 in position. The closure 142 is of circular shape facilitating adjustment of the position of the projection 144 by rotating the closure. The pumping diaphragm 140 is formed with integral inlet and outlet flap valves. An inlet flap valve 158 cooperates with a port 160 in communication with the fuel chamber 162 provided above the filter 150. The valve 158 opens into a space 164 which is in communication with the fuel chamber 138 of the pump through a passage (not shown).

The outlet flap valve 166 of the diaphragm cooperates with an outlet port 168 from the fuel chamber 138, the member 86 being formed with a space 170 to accommodate opening movements of the valve 166.

The member 86 and the carburetor body 50 are provided with registering passages or channels 172 and 174 which, with the passage 110, facilitate flow of liquid fluel to the region of the inlet valve 106 in the carburetor. A gasket 141 disposed between the peripheral region of the diaphragm 140 and the adjacent surface of the member 86 provides an effective seal.

The pumping diaphragm 140 is arranged to be vibrated or actuated by pulsations set up by differential pressures in the engine cylinder, the pulse tube connection being shown in FIGURE 4. The member 86 is fashioned with a boss portion 176, shown in FIGURE 4, fashioned with a bore 178. Disposed adjacent the boss portion 176 is a fitting 182, and a coupling sleeve or member 184 is snugly fitted or pressed into a bore in the fitting 182 and the bore 178 aligned therewith in the member 134.

The fitting 182 is provided with a tubular nipple portion 186 having a passage 187 therein. A short length of flexible tube or hose 190 is connected with a metal tube 191 and with the fitting 182, the metal tube 191 being connected with a fitting 192, shown in FIGURE 1, mounted at one side of the cylinder 14 of the engine. The fitting 192 has a tenon portion 194 which is pressfitted into a bore in a boss 1% formed on the cylinder. The fitting 192 has a passage therethrough in communication with a passage 198 opening into the interior of the engine cylinder, as shown in FIGURE 1.

It is preferable to locate the metal tube 191 adjacent a side of the engine cylinder nearest the cooling fan of the engine so that the air circulated by the cooling fan will maintain the tube at a reduced temperature to prevent heat damage to the hose 198. The passage or port 198 in the cylinder wall of the engine is located so as to be exposed to or be in communication with the combustion zone or chamber 200 defined by the cylinder when the piston is in its lowermost position, as shown in FIG- URE 1. The pump diaphragm 140 is vibrated or actuated by pulses set up by varying pressures existent in the chamber 200 during engine operation.

As the engine is of the four cylinder or Otto cycle type, the piston moving downwardly on the mixture intake cycle sets up reduced pressure in the chamber 280 which repassage 198 and tubes 191 and 190 to the pumping or pulsing chamber 136 of the pump. Upon the succeeding power stroke of the piston, the burning gases set up increased pressures in the chamber 200. When the piston moves to its lowermost position, as shown in FIGURE 1 uncovering or exposing the port or passage 198, the pressure in the cylinder is transmitted to the pumping chamber 136 to flex the diaphragm 140 in the opposite direction.

The differential pressures continuously occurring during engine operation vibrate or actuate the diaphragm 140 to pump fuel from the supply tank 202, shown in FIG- URE 1, through the tube 146 into the sump 154 through the screen or filter 159 and space 162 past the inlet and outlet flap valves 158 and 166 to maintain fuel in the passages 172, 174 and 110 adjacent the fuel inlet control valve 106 to satisfy the engine requirements as determined by aspiration in the mixing passage effective through the fuel channels and main and secondary orifices on the diaphragm to control the position of the fuel inlet valve 106.

The pumping section or frequency of vibration of the diaphragm varies dependent upon engine speed and engine load conditions. Under light loads at idling and low speed, the exhaust pressures in the cylinder are rather low, but on the inlet or suction stroke of the engine piston, the vacuum in the cylinder or combustion region 200 is comparatively high and is ample to flex or actuate the fuel pump diaphragm. Under open throttle conditions under substantial load, the vacuum in the cylinder on an inlet stroke of the piston may be too low to effect an appreciable movement or flexure of the pump diaphragm.

However, under these engine operating conditions, there is comparatively high exhaust pressure developed in the engine cylinder on the power stroke effective to vibrate or actuate the pumping diaphragm.

Thus, at light loads and low engine speeds and under increased loads and increased engine speeds, differential pressures are present to operate the diaphragm. At low speed, a high vacuum actuates the diaphragm so that there is ample fuel supply being pumped to the carburetor, and at higher engine speeds and higher loads, ample exhaust pressures in the cylinder are effective to vibrate the pumping diaphragm so that the pump under all operating conditions supplies fuel to the carburetor to satisfy all engine requirements.

The moving components of an internal combustion engine necessarily require lubrication so that there is usually present a film or small quantity of oil on the walls of the cylinder and piston.- Furthermore, the chamber or combustion zone 200 defined by the cylinder contains products of combustion, particles of carbon and other residue matter resulting from combustion. It has been found that during engine operation over extended periods of time and particularly operation of worn engines, there is a tendency for lubricant or oil and condensed products of combustion and other residue to be transmitted through the port 198, tubes 190 and 191 and passageways, shown in FIGURE 4, into the pumping or pulsing chamber 136.

An accumulation of foreign matter in the pumping chamber would impair proper functioning or vibration of the diaphragm and render the pump ineffective to deliver the requisite amount of fuel to the carburetor.

The carburetor and pump construction of the invention embodies an arrangement to prevent accumulation of foreign matter in the pulsing chamber by scavenging or purging the pulsing or pumping chamber. Referring to FIGURE 6, the member 86 is fashioned with a channel or passage 206 which is in communication with the pulsing or pumping chamber 136 by a restricted passage 208 of comparatively small size.

The passage or channel 206 is in communication with the mixing passage 52 through a series of communicating passages or channels 210, 211, 212 and 213, the outlet 215 of passage 2113 opening into the mixing passage. The orifice 215 is at the downstream side of the choke band or restricted region 54, as shown in FIGURE 5, so that when the throttle valve 72 is in open position a substantial suction or reduced pressure is effective through the restricted passage 208 and the interconnected passages 206, 210, 211, 212 and 213 to withdraw foreign matter from the pumping chamber 136.

The inlet of the restriction 208 should be disposed as close as practicable to the diaphragm 136 so that foreign matter on the diaphragm will be withdrawn and conveyed through this system of channels and discharged into the mixing passage where it is entrained in and carried by the mixture stream into the intake manifold of the engine.

Under heavy load conditions of the engine wherein comparatively high pressures are developed in the engine cylinder, the pressure pulse from the cylinder 200 is substantial and, being communicated to the pumping chamber 136 through tubes 190, 191 and associated interconnected channels, shown in FIGURE 4, is effective to scavenge the pumping chamber 136 by blowing any condensed products of combustion or other foreign matter in the chamber through the channels 208, 206, 210, 211, 212 and 213 into the Venturi of the mixing passage and carried into the combustion chamber of the engine and burned.

Under light engine loads, such as idling and low speed conditions, the exhaust pressure in the engine cylinder is rather low, but the vacuum-or reduced pressure in the cylinder or combustion zone on the intake strokes is substantial so that a reduced pressure or suction pulse of substantial magnitude is transmitted to the pumping chamber 136. Under these conditions of engine operation, air flow may be in a reverse direction and may enter through the orifice 215 and transmission of foreign matter from the engine cylinder to the pulse chamber 136 may be prevented or reduced by the back bleeding of the air through the chambers 213, 212, 211, 210, 206 and the restricted passage 208, the extent of air back bleed being determined by the size of the restriction 208.

It is to be understood that the restricted vent or scavenging passage 208 is comparatively small so as not to materially impair the pressure and suction pulses communicated to the pulse chamber 136. For example, it has been found that the restriction 208 as small in diameter as about 0.021 of an inch and as large in diameter as 0.042 of an inch may be employed for use with a relatively small four cycle engine where the pulse passage 180 is about one-eighth of an inch in diameter. However, where a pulse passage 180 is of larger size, the scavenging restriction 208 may be of increased size but should be maintained within a size range so as not to appreciably impair the transmission of pressure and suction pulses from the engine cylinder to the pulse chamber 136.

FIGURES 7 through 13 illustrate a circulatory fuel supply and carburetor construction wherein liquid fuel in a carburetor fuel chamber is maintained at a substantially constant level and fuel circulated from a supply or tank by a pulse operated pumping diaphragm to continuously replenish fuel in the carburetor fuel chamber. This form of construction eliminates the use of a fuel inlet control valve, a fuel metering diaphragm and motion transmitting means between a diaphragm and an inlet valve. In this form, the carburetor 220 is supplied with fuel from a fuel supply tank 222 disposed below the carburetor for reasons hereinafter explained.

The carburetor of this form of the invention is inclusive of a body 224 having a fuel and air mixing passage 226 in communication with an air inlet 227. The mixing passage includes a Venturi 228 having a restricted zone or choke band 230, the Venturi opening into a mixture outlet 232. The mixture outlet end of the body is fashioned with a mounting flange 234 for attachment to the flange 62 of the mixture intake manifold 40 of the engine, shown in FIGURE 1, the flange 234 being provided with openings 235 to receive securing bolts. Journaled in bores in the wall at the air inlet end is a shaft 236 supporting a choke valve 237, the shaft being equipped with a manipulating arm 238.

Journaled in bores in the wall defining the mixture outlet is a throttle shaft 240 carrying a throttle valve 241 for controlling the flow of fuel and air mixture into the engine intake manifold. Secured to a projecting end of the shaft 240 is a manipulating member 242 for operating the throttle valve. The member 242 is fashioned with an ear portion 244 having a threaded opening accommodating a screw 246, the screw being arranged to engage an abutment 248 on the body for defining the near closed or idle position of the throttle valve 241.

An expansive coil spring 249 is disposed between the head of the screw 246 and the ear portion 244 to establish friction for retaining the screw in adjusted position.

The air inlet end of the carburetor body is provided with a flange 250 having threaded bores 251 to accommodate securing screws for mounting an air filter or air cleaner (not shown) at the air inlet. The carburetor is provided with a duct or channel system for delivering liquid fuel into the mixing passage 226 from a constant supply region or chamber.

A pulse operated diaphragm pump or fuel circulating means is operated continuously during engine operation to deliver fuel from the fuel supply tank to the constant supply region or chamber in the carburetor, the arrangement including means for returning excess fuel from the constant supply region to the fuel tank. Extending across a flat surface of a boss portion 254 of the carburetor body is a pumping diaphragm 256, a gasket 257 being disposed between the diaphragm and the boss. The pumping diaphragm 256 is made of impervious material, such as synthetic rubber reinforced by glass fiber cloth or close mesh fabric.

The carburetor body 224 is fashioned with a recess forming a pulse or pumping chamber 260 which is adapted to be in communication with the port 198 provided in the cylinder wall of the engine, as shown in FIGURE 1. With reference to FIGURE 13, the pulse or pumping chamber 260 is in communication with a passage 262 and interconnecting passages 263 and 264 and a tubular spud or nipple 266. The nipple 266 is pressed into an opening formed in a fitting or member 268 secured to the carburetor body by screws 370 The tubular member or coupling 266 is adapted to telescopingly receive an end of a flexible tube 190 which is adapted to be connected by a tube 191' with the port 198 of the character shown in FIGURE 1.

Through this arrangement, varying or differential pressures in the engine cylinder are transmitted to the pumping chamber 260 for flexing or vibrating the diaphragm 256. The member or plate 268 is of generally rectangular configuration, as shown in FIGURE 9, and is formed with a cavity or recess 272 disposed opposite the cavity 260 providing the fuel chamber of the pump. The pump construction illustrated herein is of the general character disclosed in my United States patent, No. 2,796,838 wherein flap valves integrally formed on the diaphragm control fuel flow into and out of the fuel chamber 272.

As shown in the semi-schematic view, FIGURE 10, a flap valve 274 formed on the diaphragm 256 is arranged to control an inlet port 276. A nipple or sleeve 277 is pressed or fitted into an opening in registration with the port 276, the nipple 277 being connected by means of a flexible tube 278 with a tubular member 279 extending through an opening in the top wall of the fuel tank 222, the tube 279 terminating adjacent the bottom of the fuel tank 222. The tube 279 is prefearbly welded or brazed to a flange 280 defiining the opening in the tank receiving the tube 279.

The flexible tube or hose 278 may be fashioned of synthetic rubber, resinous plastic or other material resistant to the effects of hydrocarbon fuels. The carburetor body 224 is formed with a recess or clearance space 282 to accommodate a movement of the flap valve 274, the recess 282 being in communication with interconnecting passages 283 and 284, the latter opening into the fuel chamber 2721 The diaphragm 256 is fashioned with a second flap valve 286 disposed adjacent an outlet port 288 which is in communication with the fuel chamber 272 by a passage 290.

The body 224 is formed with a space 290 to acccommodate movement of the outlet flap valve 286. Formed in the body above the space 290 is a recess 292 which is preferably of circular shape, the upper end of which is closed by Welsh plug 294. A downwardly extending passage 296 is in communication with the recess 292 and is in communication with the space 290 by a restricted passage 298. The body 224 is fashioned with an over flow passage 300, particularly shown in FIGURE 10, opening into the recess 292, the recess providing a crossover channel between the passage 296 and the overflow passage 300. The member 268 is fashioned with a bore 302 in registration with the overflow passage 300, a nipple or sleeve 304 being pressed into the bore 302.

The fuel tank 222 is provided with a tubular member or nipple 306 which is brazed or secured to a flange 308 defining an opening in the top wall of the fuel tank accommodating the nipple 306. Telescoped over the nipples 304 and 306 is a flexible tubular member or hose 310 of the same character as the hose 278. The channel 300, the bore 302, the nipples 304 and 306 and the tubular member 310 provide an overflow channel for returning excess fuel from the recess or crossover chamber 292 to the fuel tank 222. The Welsh plug 294 closing the supplemental fuel chamber 292 is provided with a small vent opening 312 to establish atmospheric pressure in the supplemental chamber 292.

The pulsing action or vibration of the diaphragm 256, in cooperation with the inlet and outlet flap valves 274 and 286, provides a pumping arrangement for continuously pumping fuel from the tank 222 through the fuel chamber 272 of the pump and into the supplemental or crossover passage 292 whereby the chamber 296 is always filled with liquid fuel, the excess fuel delivered to the supplemental chamber 292 flowing back into the tank 222 through the return channel system. Through this arrangement a constant fuel level is maintained in the fuel channel system of the carburetor at a level determined by the floor of the supplemental chamber 292.

Thus, during operation of the engine and pulsation of the pumping diaphragm 256, fuel flow is assured into the passage 296. The chamber 292 provides a constant head of fuel in the passage 296 for delivery through a fuel delivery duct or channel system into the mixing passage 226. The carburetor body 224 is provided with a main fuel passage 314, the outlet of which forms a main nozzle or fuel delivery orifice 316, shown in FIGURES l1 and 12, the orifice opening into the restricted region 230 of the Venturi.

The carburetor body is fashioned with a boss portion 318 provided with a bore accommodating a manually adjustable valve member 320, a portion of the bore being threaded to receive a threaded portion 321 of the valve body or member 320. The valve member 320 is provided with a comically-shaped or needle valve portion 322 extending into the passage 314 at its region of communication with the chamber 296. The valve body 320 is provided with a knurled head 324 to facilitate manual adjustment. A sealing gasket 326 surrounds the valve body 320.

An expansive coil spring 328 disposed between the head 324 of the valve body and the carburetor body provides friction for retaining the valve in adjusted position. Rotation of the valve member 320 adjusts the position of the needle valve portion 322 relative to the passage 314 to meter or regulate delivery of fuel through the main orifice 316.

The charge forming apparatus or carburetor, shown in FIGURES 11 and 12, is provided with a secondary fuel delivery system for engine idling and low speed operation. As shown in FIGURE 11, the body 224 is fashioned with an auxiliary chamber 332 which is in communication with the mixture region of the mixing passage by an engine idling orifice 334 and a low speed orifice 336. The carburetor body is provided with a drilled passage 338 which is in communication with the auxiliary chamber 332 through a restricted passage 340 whereby fuel is conveyed to the orifices 334 and 336 from the passage 296.

One end of the auxiliary chamber 332 is closed by a Welsh plug 342, and the outer end of the drilled passage 338 closed by a shot or plug 344. It will be apparent that the adjustable needle valve 322 meters or regulates the fuel flow to both the main orifice 316 and the secondary orifices 334 and 336.

As the fuel pump diaphragm 256 is continuously flexed by varying pressures in the combustion region provided by the cylinder of the engine when the latter is in operation, fuel is continuously pumped or circulated through the passages 290 and 298 into the vertical reservoir passage or passage 296 whereby the chamber 296 is maintained filled with fuel to the level of overflow at the floor of the overflow or crossover chamber 292.

This arrangement provides a constant fuel supply in the passage 296 of a depth to the outlet of this passage into the chamber 292 so that there is a head of fuel at all times available for delivery through the main orifice or secondary orifices.

It should be noted that the main and secondary orifices and the channels 314 and 338 are below the level of fuel maintained in the supply chamber or space 296.

Means is also provided for scavenging foreign matter or condensed products of combustion from the pumping or pulsing chamber 269. Referring to FIGURE 13, there is provided a restricted channel or passage 348 between the mixing passage and the pumping or pulse chamber 260, the entrance end 350 of the restricted passage opening into the pumping chamber 260 at a region close to the diaphragm. The restricted scavenging passage 348 is comparatively small so as not to appreciably impair the effect of pressure variations transmitted to the pumping chamber from the engine cylinder.

The scavenging passage 348 functions in substantially the same manner as the scavenging passage 213 in the form of carburetor illustrated in FIGURE 6. Under low speed operations of the engine where the intake suction is high, the reduced pressure on the intake suction strokes of the piston causes air from the mixing passage to flow or back bleed through the scavenging passage 348 into the chamber 260 to promote scavenging of foreign matter through the pasasges 262 and 263 and through the tube into the engine cylinder.

Under high pressures transmitted to the pumping chamber 260 from the combustion chamber of the engine at higher engine speeds, the pressures in the pulse chamber 260 cause foreign matter and condensed products of combustion in the chamber to be expelled through the scavenging passage 348 into the mixing passage for delivery into the engine intake manifold.

With particular reference to FIGURE 11, it should be noted that the needle valve 322 meters or regulates fuel delivery to both the main and secondary orifice systems. When the throttle is in idling position or partial open position whereby fuel is delivered through the idle orifice 334 or low speed orifice 336, air may flow from the mixing passage through a portion of the channel 314 for admixing with the fuel flowing to the secondary orifices whereby an emulsion of air and fuel is delivered to the secondary orifices. The engine idling orifice 334, the low speed orifice 336 and the restriction 340 are of required sizes to obtain satisfactory delivery of fuel for engine idling and low speed operation without necessitating the use of a separate adjustment of fuel for the secondary orifice system.

From the foregoing it will be apparent that the method and apparatus disclosed provides an effective fuel pumping and charge forming means for supplying fuel to a four cycle engine from pressure pulses derived from the combustion chamber or cylinder of the engine and all mechanical means for actuating a pump diaphragm are eliminated.

The arrangements disclosed are reliable in operation and through the use of scavenging means foreign matter is prevented from accumulating in the pumping chamber. While a single cylinder engine of the four cycle type is illustrated, it is to be understood that the system of the invention may be used with multi-cylinder engines, the pulse line or tube being connected with only one cylinder.

-It is apparent that, within the scope of the invention, modifications and different arrangements may be made other than as herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

I claim:

1. A fuel feed system for an internal combustion engine of the reciprocating piston type, said system including a fuel supply tank adapted to contain liquid fuel, a charge forming device connected with the engine and having a mixing passage arranged to deliver combustible mixture to the engine, said charge forming device including a fuel compartment, fuel channel means for conveying fuel from the compartment to the mixing passage, fuel pumping means including a flexible member defining a variable volume pumping chamber and a fuel chamber, means including a duct arranged to deliver fuel from the fuel chamber to the fuel compartment in the charge forming device, passage means connecting the pumping chamber with the engine cylinder, the entrance of said passage means in the cylinder being arranged to be uncovered when the piston approaches its maximum stroke position whereby varying fluid pressures in the engine cylinder are transmitted by said passage means to the pumping chamber for effecting relative movement of the flexible member, and a restricted vent passage between the pumping chhamber and the mixing passage of the charge forming device for scavenging foreign matter from the pumping chamber.

2. A fuel feed system for an internal combustion engine of the cylinder and reciprocating piston type, said system including a fuel supply tank adapted to contain liquid fuel, acharge forming device connected with the engine and having a mixing passage arranged to deliver combustible mixture to the engine, said charge forming device including a flexible diaphragm defining an unvented fuel compartment, fuel channel means for conveying fuel from the compartment to the mixing passage, a fuel inlet valve for the compartment, motion transmitting means between the diaphragm and the inlet valve whereby aspiration in the mixing passage influences the position of the inlet valve to control fuel flow into the fuel compartment, fuel pumping means including a flexible member defining a variable volume pumping chamber and a fuel chamber, means including a duct arranged to convey fuel from the fuel chamber to the region of the fuel inlet valve in the charge forming device, a port in the cylinder wall of the engine, passage means connecting the pumping chamber with the port, said port being arranged to be uncovered when the piston approaches its maximum stroke position whereby varying fluid pressures in the engine cylinder are transmitted to the pumping chamber for effecting relative movement of the flexible member, and a restricted vent passage between the pumping chamber and the mixing passage of the charge forming device for scavenging foreign matter from the pumping chamber.

3. In combination, charge forming apparatus for supplying combustible mixture to an internal combustion engine of the cylinder and reciprocating piston type, said charge forming apparatus including a body formed with a mixing passage, orifice means for delivering liquid fuel into the mixing passage, said body having a fuel receiving Well arranged to maintain fuel adjacent the fuel delivery orifice means, a fluid pressure actuated fuel pump associated with the charge forming apparatus for supplying fuel from a fuel supply tank to the fuel receiving well, channel means connecting the fuel well with the fuel delivery orifice means, overflow duct means connecting the fuel well with the fuel supply tank, said fuel pump including a flexible member defining a variable volume pumping chamber and a fuel chamber, passage means arranged to convey fuel from the fuel chamber to the fuel well, tubular means connecting the pumping chamber with a port in the engine cylinder, the port in the cylinder being arranged to be uncovered when the piston approaches its maximum stroke position whereby varying fluid pressures in the engine cylinder are transmitted to the pumping chamber, and a restricted vent passage between the pumping chamber and the mixing passage of the charge forming apparatus for scavenging foreign matter from the pumping chamber.

References Cited by the Examiner UNITED STATES PATENTS 1,146,134 7/1915 Carter 123--139.9 1,325,180 12/1919 Weinberg 123119 X 1,418,548 6/1922 Edwards 123139.9 1,953,808 4/1934 Kenneweg 123-136 2,598,147 5/1952 Tescher.

2,796,838 6/1957 Phillips 123-1398 X 3,085,620 4/1963 Johnson 123-139 X MARK NEWMAN, Primary Examiner.

RICHARD B. WILKINSON, Examiner. 

1. A FUEL FEED SYSTEM FOR AN INTERNAL COMBUSTION ENGINE OF THE RECIPROCATING PISTON TYPE, SAID SYSTEM INCLUDING A FUEL SUPPLY TANK ADAPTED TO CONTAIN LIQUID FUEL, A CHARGE FORMING DEVICE CONNECTED WITH THE ENGINE AND HAVING A MIXING PASSAGE ARRANGED TO DELIVER COMBUSTIBLE MIXTURE TO THE ENGINE, SAID CHARGE FORMING DEVICE INCLUDING A FUEL COMPARTMENT, FUEL CHANNEL MEANS FOR CONVEYING FUEL FROM THE COMPARTMENT TO THE MIXING PASSAGE, FUEL PUMPING MEANS INCLUDING A FLEXIBLE MEMBER DEFINING A VARIABLE VOLUME PUMPING CHAMBER AND A FUEL CHAMBER, MEANS INCLUDING A DUCT ARRANGED TO DELIVER FUEL FROM THE FUEL CHAMBER TO THE FUEL COMPARTMENT IN THE CHARGE FORMING DEVICE, PASSAGE MEANS CONNECTING THE PUMPING CHAMBER WITH THE ENGINE CYLINDER, THE ENTRANCE OF SAID PASSAGE MEANS IN THE CYLINDER BEING ARRANGED TO BE UNCOVERED WHEN THE PISTON APPROACHES ITS MAXIMUM STROKE POSITION 